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Title: SU-F-T-630: Energy Spectral Study On Lipiodol After Trans-Arterial Chemoembolization Using the Flattened and Unflattened Photon Beams

Abstract

Purpose: SBRT combining transarterial chemoembolization with Lipiodol is expected to improve local control. Our showed that the dose enhancement effect in the Lipiodol with 10X flattening filter free (FFF) was inserted. This study was to investigate the energy fluence variations of electron in the Lipiodol using flattened (FF) and FFF beams. Methods: FF and FFF for 6X and 10X beams by TrueBeam were used in this study. The Lipiodol (3 X 3 X 3 cm{sup 3}) was located at the depth of 5 cm in water, the dose enhancement factor (DEF) and energy fluence were calculated by Monte Carlo (MC) calculations (PHITS). Results: DEFs with FF and FFF of 6X were 17.1% and 24.3% at rebuild-up region in the Lipiodol (5.3cm depth), 7.0% and 17.0% at the center of Lipiodol (6.5cm depth), and −13.2% and −8.2% at behind Lipiodol (8.3cm depth). DEFs with FF and FFF of 10X were 21.7% and 15.3% at rebuild-up region, 8.2% and 10.5% at the center of Lipiodol, and −14.0% and −8.6% at behind Lipiodol. Spectral results showed that the FFF beam contained more low-energy (0–0.3MeV) component of electrons than FF beam, and FF beam contained more high-energy (over 0.3MeV) electrons than FFF beam inmore » Lipiodol. Behind the Lipiodol, build-down effect with FF beam was larger than FFF beam because FF beam contained more high energy electrons. The difference of DEFs between FFF and FF beams for 6X were larger than for 10X. This is because 10X beam contained more high-energy electrons. Conclusion: It was found that the 6XFFF beam gives the largest change of energy fluence and the largest DEF in this study. These phenomena are mainly caused by component of low-energy electrons, and this energy is almost correspond to the boundary of photo electronic dominant and Compton scattering dominant region for photon beams.« less

Authors:
 [1];  [2]; ;  [3];  [2]; ; ;  [3]; ; ; ; ; ;  [1];  [4]
  1. Radiation Therapy Section, Department of Clinical Support, Hiroshima University Hospital, Hiroshima (Japan)
  2. (Japan)
  3. Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima (Japan)
  4. Department of Nuclear Engineering and Management, School of Engineering, University of Tokyo, Tokyo (Japan)
Publication Date:
OSTI Identifier:
22649190
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; BLOOD VESSELS; COMPTON EFFECT; LIPIODOL; MONTE CARLO METHOD; PHOTON BEAMS; RADIATION DOSES; FUNDAMENTAL INTERACTIONS

Citation Formats

Kawahara, D, Medical and Dental Sciences Course, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Ozawa, S, Nagata, Y, Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Saito, A, Nishio, T, Suzuki, T, Hioki, K, Masuda, H, Okumura, T, Ochi, Y, Nakashima, T, Ohno, Y, and Tanaka, S. SU-F-T-630: Energy Spectral Study On Lipiodol After Trans-Arterial Chemoembolization Using the Flattened and Unflattened Photon Beams. United States: N. p., 2016. Web. doi:10.1118/1.4956815.
Kawahara, D, Medical and Dental Sciences Course, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Ozawa, S, Nagata, Y, Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Saito, A, Nishio, T, Suzuki, T, Hioki, K, Masuda, H, Okumura, T, Ochi, Y, Nakashima, T, Ohno, Y, & Tanaka, S. SU-F-T-630: Energy Spectral Study On Lipiodol After Trans-Arterial Chemoembolization Using the Flattened and Unflattened Photon Beams. United States. doi:10.1118/1.4956815.
Kawahara, D, Medical and Dental Sciences Course, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Ozawa, S, Nagata, Y, Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Saito, A, Nishio, T, Suzuki, T, Hioki, K, Masuda, H, Okumura, T, Ochi, Y, Nakashima, T, Ohno, Y, and Tanaka, S. 2016. "SU-F-T-630: Energy Spectral Study On Lipiodol After Trans-Arterial Chemoembolization Using the Flattened and Unflattened Photon Beams". United States. doi:10.1118/1.4956815.
@article{osti_22649190,
title = {SU-F-T-630: Energy Spectral Study On Lipiodol After Trans-Arterial Chemoembolization Using the Flattened and Unflattened Photon Beams},
author = {Kawahara, D and Medical and Dental Sciences Course, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima and Ozawa, S and Nagata, Y and Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima and Saito, A and Nishio, T and Suzuki, T and Hioki, K and Masuda, H and Okumura, T and Ochi, Y and Nakashima, T and Ohno, Y and Tanaka, S},
abstractNote = {Purpose: SBRT combining transarterial chemoembolization with Lipiodol is expected to improve local control. Our showed that the dose enhancement effect in the Lipiodol with 10X flattening filter free (FFF) was inserted. This study was to investigate the energy fluence variations of electron in the Lipiodol using flattened (FF) and FFF beams. Methods: FF and FFF for 6X and 10X beams by TrueBeam were used in this study. The Lipiodol (3 X 3 X 3 cm{sup 3}) was located at the depth of 5 cm in water, the dose enhancement factor (DEF) and energy fluence were calculated by Monte Carlo (MC) calculations (PHITS). Results: DEFs with FF and FFF of 6X were 17.1% and 24.3% at rebuild-up region in the Lipiodol (5.3cm depth), 7.0% and 17.0% at the center of Lipiodol (6.5cm depth), and −13.2% and −8.2% at behind Lipiodol (8.3cm depth). DEFs with FF and FFF of 10X were 21.7% and 15.3% at rebuild-up region, 8.2% and 10.5% at the center of Lipiodol, and −14.0% and −8.6% at behind Lipiodol. Spectral results showed that the FFF beam contained more low-energy (0–0.3MeV) component of electrons than FF beam, and FF beam contained more high-energy (over 0.3MeV) electrons than FFF beam in Lipiodol. Behind the Lipiodol, build-down effect with FF beam was larger than FFF beam because FF beam contained more high energy electrons. The difference of DEFs between FFF and FF beams for 6X were larger than for 10X. This is because 10X beam contained more high-energy electrons. Conclusion: It was found that the 6XFFF beam gives the largest change of energy fluence and the largest DEF in this study. These phenomena are mainly caused by component of low-energy electrons, and this energy is almost correspond to the boundary of photo electronic dominant and Compton scattering dominant region for photon beams.},
doi = {10.1118/1.4956815},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = 2016,
month = 6
}
  • BackgroundThere is still no consensus about the best chemotherapeutic agent for transarterial chemoembolization (TACE). A recent in vitro study demonstrated that idarubicin, an anthracycline, was by far the most cytotoxic drug on human hepatocellular carcinoma (HCC) cell lines. Idarubicin is much more lipophilic than doxorubicin, leading to higher cell penetration through lipidic membranes and greater accumulation of the drug in the lipiodol. Furthermore, idarubicin has the ability to overcome multidrug resistance. Therefore, we designed this pilot human study to evaluate the safety and efficacy of lipiodol TACE using idarubicin.MethodsIn 21 consecutive patients treated by lipiodol TACE with idarubicin (10 mg)more » for HCC, safety data, tumor response (Response Evaluation Criteria in Solid Tumors, mRECIST), time to treatment failure (TTTF), and overall survival were evaluated.ResultsPostembolization syndrome was observed after 30.9 % (17 of 55) of sessions. No patient died from a TACE-related complication. No hematological grade 3-5 adverse event was observed. At least one grade 3 or higher adverse event occurred in 19 % (4 of 21) of patients. On imaging, no progression was encountered; four patients (24 %) exhibited stable disease, 12 (57 %) exhibited a partial response, and five (19 %) exhibited a complete response. Median TTTF was 16.7 months (Kaplan-Meier analysis). At 6 months, 94.7 % (95 % confidence interval [CI] 68.1-99.2) of patients did not reach treatment failure, whereas treatment failure was not reached in 50.6 % (95 % CI 21.6-73.9) of patients at 1 year. Overall survival was 83.5 % (95 % CI 57-94.4) at 1 year.ConclusionIdarubicin seems safe and effective in lipiodol TACE of HCC. This warrants further study to determine the potential of this drug to replace doxorubicin for TACE.« less
  • Purpose: This study investigates the spectra of surface photon energy and energy fluence in the bone heterogeneity and beam obliquity using flattened and unflattened photon beams. The spectra were calculated in a bone and water phantom using Monte Carlo simulation (the EGSnrc code). Methods: Spectra of energy, energy fluence and mean energy of the 6 MV flattened and unflattened photon beams (field size = 10 × 10 cm{sup 2}) produced by a Varian TrueBEAM linear accelerator were calculated at the surfaces of a bone and water phantom using Monte Carlo simulations. The spectral calculations were repeated with the beam anglesmore » turned from 0° to 15°, 30° and 45° in the phantoms. Results: It is found that the unflattened photon beams contained more photons in the low-energy range of 0 – 2 MeV than the flattened beams with a flattening filter. Compared to the water phantom, both the flattened and unflattened beams had slightly less photons in the energy range < 0.4 MeV when a bone layer of 1 cm is present under the phantom surface. This shows that the presence of the bone decreased the low-energy photons backscattered to the phantom surface. When the photon beams were rotated from 0° to 45°, the number of photon and mean photon energy increased with the beam angle. This is because both the flattened and unflattened beams became more hardened when the beam angle increased. With the bone heterogeneity, the mean energies of both photon beams increased correspondingly. This is due to the absorption of low-energy photons by the bone, resulting in more significant beam hardening. Conclusion: The photon spectral information is important in studies on the patient’s surface dose enhancement when using unflattened photon beams in radiotherapy.« less
  • The purpose of this study was to retrospectively clarify the current status in Japan of TACE using Lipiodol together with anticancer agents to treat hepatocellular carcinoma (HCC). We retrospectively surveyed 4,659 (average annual total) procedures for HCC over the years 2002-2004 at 17 institutions included in the TACE Study Group of Japan. The survey included six questions that were related mainly to TACE and Lipiodol for HCC treatment. The most frequently applied among the 4,659 procedures at the 17 institutions were TACE (2,310; 50%) and local ablation (1,395; 30%). Five of the institutions applied 201-300 procedures and 4 applied 101-200.more » Lipiodol was used in 'all procedures' and in '90% or more' at seven and nine institutions, respectively. Almost all institutions applied 4-6 (mean, 5) ml of Lipiodol during TACE to treat tumors 5 cm in diameter. In conclusion, this survey clarified that TACE using Lipiodol and anticancer agents is a popular option for HCC treatment in Japan.« less
  • Purpose: Aim of this study is to compare the dose volume characteristics of 6X FFF (flattening Free Filter) Arc and 6X FB (flattened Beam) arc photon plans in SBRT technique. Methods: Eight patients who received linear Accelearator-based SBRT were retrospectively included in this study. A dose of 50 Gy was given to the target in five fractions. Same data set was used to generate plans for both FFF and FB. ITV was generated using maximum intensity projection and critical structures were derived using average intensity projection. PTV obtained by giving 0.5cm margin to ITV. Results: While both modalities can providemore » satisfactory target dose coverage, the dose to PTV was more heterogeneous in FFF than 6X FB plans in all cases. The doses in all plans were well below institutional constraints for both modalities. Comparing the results of Homogeneity Index(HI), Conformity Index(CI), PTV-D80% volume, D50% volume and D20% volume (Table-1 ) for both techniques, found all the indices are within limits of RTOG guidelines but the 6X FFF is superior in sparing normal tissues in compare with FB. In all cases studied, more treatment time was required for FB treatment delivery for a given prescription. The results indicate that for large dose delivery FFF is preferable as volumetric parameters like HI and CI are better and dose can be delivered in a short span of time. Conclusion: Both Flattened and Unflattened beam SBRT systems can provide adequate dose coverage for target tumor. While the unflattened beams deliver less normal tissue dose than Flattened beams in all cases. The magnitude of differences in normal tissue dose between both modalities was due to beam characterization of the beams. Flattened beam requires more Monitor Units to deliver similar target prescription to the tumor than unflattened beam SBRT systems. The results of this study may provide a general guideline for patient and treatment modality selection based on volumetric, tumor control and normal tissue sparing considerations.« less
  • Purpose: To compare contribution and accuracy of delivery for two flattening filter free (FFF) beams of the nominal energy 6 and 10 MV and a 6 MV flattened beam for early stage lung cancer. Methods: For each of 11 patients with stage I nonsmall cell lung cancer three volumetric modulated arc therapy plans were prepared utilizing a 6 MV flattened photon beam (X6FF) and two nonflattened beams of nominal energy 6 and 10 MV (X6FFF, X10FFF). Optimization constraints were set to produce dose distributions that meet the criteria of the RTOG-0915 protocol. The radiation schedule used for plan comparison inmore » all patients was 50 Gy in five fractions. Dosimetric parameters of planning target volume (PTV) and organs-at-risk and delivery times were assessed and compared. All plans were subject to verification using Delta{sup 4} unit (Scandidos, Sweden) and absolutely calibrated gafchromic films in a thorax phantom. Results: All plans had a qualitatively comparable outcome. Obtained dose distributions were conformal (CI < 1.17) and exhibited a steep dose fall-off outside the PTV. The ratio of monitor units for FFF versus FF plans in the authors' study ranged from 0.95 to 1.21 and from 0.93 to 1.25 for X6FFF/X6FF and X10FFF/X6FF comparisons, respectively. The ratio systematically increased with increasing size of the PTV (up to +25% for 150 cm{sup 3} PTV). Yet the integral dose to healthy tissue did not follow this trend. Comparison of cumulative dose volume histograms for a patient's body showed that X6FFF plans exhibit improved conformity and reduced the volume of tissue that received more than 50% of the prescription dose. Parameters related to dose gradient showed statistically significant improvement. CI{sub 50%}, CI{sub 60%}, CI{sub 80%}, and CI{sub 100%} were on average reduced by 4.6% (p < 0.001), 4.6% (p = 0.002), 3.1% (p = 0.002), and 1.2% (p = 0.039), respectively. Gradient measure was on average reduced by 4.2% (p < 0.001). Due to dose reduction in the surrounding lung tissue, the V{sub 20} {sub Gy} and V{sub 12.5} {sub Gy} were reduced by 5.5% (p = 0.002) and 4.5% (p < 0.001). These dosimetric improvements in the fall-off were not observed for the X10FFF plans. Differences in sparing of normal tissues were not found to be statistically significant for either of the two FFF beams. Mean beam-on times were 111 s (2SD = 11 s) for X10FFF, 128 s (2SD = 19 s) for X6FFF, and X6FF plans required on average 269 s (2SD = 71 s). While the mean dose rate was 1555 ± 264 and 1368 ± 63 MU/min, for X10FFF and X6FFF, plans using the conventional X6FF were delivered with the constant maximum dose rate of 600 MU/min. Verification of all plans showed acceptable and comparable results for all plans in homogeneous as well as heterogeneous phantoms. Mean GS (3%, 2 mm) using the Delta{sup 4} phantom were 98.9% (2SD = 3.2%), 99.2% (2SD = 2.3%), and 99.2% (2SD = 2.3%) for X6FFF, X6FF, and X10FFF modalities. Verification using a thorax phantom showed GS > 98% in all cases. Conclusions: The use of FFF beams for stereotactic radiation therapy of nonsmall cell lung cancer patients yielded dose distributions qualitatively comparable to flattened beams and significantly reduced treatment delivery time. Utilizing the X6FFF beam improved conformity of dose distribution. On the other hand, X10FFF beam offered a slight improvement in treatment efficiency, and lower skin and peripheral dose. All effects were relatively small.« less